Highly Stretchable, Tough, Resilient, and Antifatigue\nHydrogels Based on Multiple Hydrogen Bonding Interactions Formed by\nPhenylalanine Derivatives

Abstract

Noncovalent\ncross-linked hydrogels with promising mechanical properties\nare on demand for applications in tissue engineering, flexible electronics,\nand actuators. However, integrating excellent mechanical properties\nwith facile preparation for the design of hydrogen bond cross-linked\nhydrogels is still challenging. In this work, an advanced hydrogel\nwas prepared from acrylamide and <i>N</i>-acryloyl phenylalanine\nby one-pot free-radical copolymerization. Owing to hydrophobicity-assisted\nmultiple hydrogen bonding interactions among phenylalanine derivatives,\nthe hydrogels exhibited fascinating mechanical behaviors: tensile\nstrength of 0.35 MPa, elongation at break of 2100%, tearing energy\nof 1134 J/m², and compression strength of 3.56 MPa. The\nhydrogels also showed robust elasticity and fatigue resistance, and\nthe compression strength did not show any decline, even after 100\nsuccessive cycles, as well as promising self-recovery property. In\naddition, the cytotoxicity test in vitro proved that the hydrogel\nshowed good biocompatibility with normal human liver cells (LO2 cells).\nThe excellent stretchability, robust elasticity, high toughness, fatigue\nresistance, and biocompatibility of the hydrogel demonstrated its\nvast potential in the biomedical field and flexible electronic devices.